Uniform Identification for the Search(1/3)

Uniform Identification for the Search(2/3)

IfcCableSegment has also unique URI:

https://identifier.buildingsmart.org/uri/buildingsmart/ifc-4.3/class/IfcCableSegmentCABLESEGMENT

Uniform Identification for the Search(3/3)

Non-unique identification violates FAIR Findability principle

F1: (Meta)data are assigned a globally unique and persistent identifier

Equal Data Retrieved from Different API (1/2)

We have compared three representations returned by the bSDD server:

• JSON from the GraphQL API
  • https://test.bsdd.buildingsmart.org/graphiql/,
• JSON from the REST (entity) API
  • curl https://identifier.buildingsmart.org/uri/buildingsmart/ <domain>/class|prop/<name> and
• RDF from the REST (entity) API
  • curl -Haccept:text/turtle \\ https://identifier.buildingsmart.org/uri/buildingsmart/ <domain>/class|prop/<name>

Equal Data Retrieved from Different API (2/2)

We selected entities of each class that have the maximum number of filled fields, and compared the results returned by each API.

The differences are here:

Improve URL Structure and Consistency (1/7)

Recommendations on ontology URI design, including versioning and opaque URIs to maintain evolution and multilingualism inherent to bSDD, are described in Garijo & Poveda-Villalon, 2020.

Almost all bSDD domain URLs now have the same structure: https://identifier.buildingsmart.org/uri/<org>/<domain>-<version>

URIs can be more ``hackable’’, allowing users to navigate the hierarchy by pruning the URI: https://identifier.buildingsmart.org/uri/<org>/<domain>/<version>

Improve URL Structure and Consistency (2/7)

• In some cases, the <org> is repeated in the <domain> part
• In some cases, the <org> name doesn’t quite mesh with the domain name, perhaps due to the way bSDD allocates <org> identifiers to bSDD contributors
  • bim-de/DINSPEC91400: the publisher of this spec is DIN (the German standards organization), not the bim-de initiative
  • digibase/volkerwesselsbv: bimregister.nl news from 2018 suggest that digibase is a new company/initaitive within Volker Wessel
  • digibase/nen2699: the publisher of this spec is NEN (the Netherlands standards organization), not the digibase company/initiative
  • digibase/digibasebouwlagen: perhaps the org name digibase should not be repeated as the prefix of the domain bouwlagen (building layers)

Improve URL Structure and Consistency (3/7)

• Explicate domain versions:

https://identifier.buildingsmart.org/uri/acca/ACCAtest-0.1

can become

https://identifier.buildingsmart.org/uri/acca/ACCAtest/0.1

A new entity DomainVersion can provide linking all versions of a domain to its master Domain entity.

Improve URL Structure and Consistency (4/7)

• Declare URLs to be ID and use a mandatory field id
  • Most GraphQL implementations call this field simply id, whereas bSDD uses namespaceUri
  • Many nodes do not have their own namespaceUri field, or it is not fully populated

Improve URL Structure and Consistency (5/7)

• Remove the overlap of Entity Classes with classificationTypes

The key field classificationType specifies the kind of classification.

Examples of unusual classifications:

https://identifier.buildingsmart.org/uri/ATALANE/REX-OBJ-1.0/class/589b06ad-f802-468b-939c-e60436601a7a is a “REFERENCE_DOCUMENT” with name “décret 2011-321 (23/03/2011)”.

Why is it not a ReferenceDocument entity?

Improve URL Stucture and Consistency (6/7)

• All entities should have URL

All significant classes should have ID, which in the case of RDF data is the node URL.

However, many bSDD classes don’t have such a field:

• Domain, Property, Classification do have namespaceUri
• Country, Language, Unit don’t have an ID but have a field (code, isocode) that can be used to make an ID, when prepended with an appropriate prefix.

Improve URL Stucture and Consistency (7/7)

Property and ClassificationProperty are two different classes, but the latter does not have a distinct URL in GraphQL and JSON.

The same URL is overloaded to identify entities of both classes.

ClassificationProperty are thus “second class” entities and are not returned separately by the JSON or RDF entity API, but only as part of the respective Classification

curl https://identifier.buildingsmart.org/uri/buildingsmart/ifc-4.3/class/IfcCableSegmentCABLESEGMENT/ACResistance

{"":["Classification with namespace URI
 'https://identifier.buildingsmart.org/uri/buildingsmart/ifc-4.3/class/IfcCableSegmentCABLESEGMENT/ACResistance'
  not found"]}

Modelling issues (1/8): Unify Solutions to Model Complex Properties

• However, connectedPropertyCodes is defined only for Property
• More importantly, these key values are never used
• connectedProperty is used only on 7 Properties (and not ClassificationProperties)

Instead of using connectedPropertyCodes to describe complex properties, some providers have used classifications with the type COMPOSED_PROPERTY.

Modelling issues (2/8): Improve Modelling of Dynamic Properties

12385 Properties are declared as isDynamic (135250 are not).

However, the field dynamicParameterPropertyCode (used to compute the dynamic property) is always empty, so how can one know which “sub-properties” to use?

Additionally, dynamicParameterPropertyCodes is String, but should be [Property], i.e. an array of Properties .

Modelling issues (4/8): Add More Entities

bSDD includes numerous string attributes (codes or URLs) that should be converted to relations (object fields) to improve the connectedness of the bSDD GraphQL graph

Modelling issues (5/8): Use Class Inheritance

Property and ClassificationProperty: differ in only 5 fields:

• connectedPropertyCodes (String) and relations (PropertyRelation) belong uniquely to Property
• isRequired (Boolean), isWritable (Boolean), predefinedValue (String), propertySet (String) and symbol (String) below uniquely to ClassificationProperty.

Since there are no rules on which fields of Property to reuse in ClassificationProperty, the latter type copies most of the fields from the former.

Modelling issues (6/8): Improve Representation of PropertyValues

PropertyValue and ClassificationPropertyValue are structured values with rich fields: code, value, namespaceUri, description, sortNumber, allowing to:

However, most structured values we’ve seen have only code, value.

This has multiple problems:

• Individual values have no description (description is not filled out)
• Some values are described in the property definition, intermingling multiple descriptions together
• The “standard” values NOTKNOWN, OTHER, UNSET are not described at all.
• Values have no namespaceUri, precluding unique identification.

Implementing Improvements

We implemented a lot (but not all) of the improvements suggested above by using the following process:

• Fetching bSDD data as JSON
• Converting it to RDF using SPARQL Anything
• Loading it to GraphDB
• Refactoring the RDF using SPARQL Update

The results are available at the endpoint

Conclusions and Future Work

Here are further ideas for improvement:

• improvement of bSDD ontology
• implement more radical data model refactoring to convert “strings” (countries, reference documents, etc.) into “things”
• link bSDD units of measure to QUDT ontology
• perform deeper data quality analysis using SHACL shapes generation and validation provided by Ontotext Platform Semantic Objects
• address and resolve more data quality issues, including
  • seeking correlation between dimension vectors, units of measure and physical quantity,
  • parsing out enumeration values from Property/ClassificationProperty descriptions and creation of corresponding PropertyValue lists
• make more graph visualizations
• obtain more interesting statistics using SPARQL

Acknowledgements

Funding: ACCORD project, Horizon Europe, grant #101056973

Data: buildingSMART Data Dictionary (bSI credits: Leon van Berlo, Artur Tomczak, Erik Baars)

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• Ontotext GraphDB
• Ontotext Platform Semantic Objects